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Re: [OM] More on DOF and focal length (by Ctein)

Subject: Re: [OM] More on DOF and focal length (by Ctein)
From: Jan Steinman <Jan@xxxxxxxxxxxxxx>
Date: Sun, 28 Jun 2009 16:52:50 -0700
> From: Chuck Norcutt <puhpxabephgg@xxxxxxxxxxxxxxxx>
>
> Very timely.  Jan and Mike should find this interesting.  Here's  
> more on
> DOF and focal length (by Ctein) from The Online Photographer:
> <http://theonlinephotographer.typepad.com/the_online_photographer/2009/06/depth-of-field-hellthe-sequel.html
>  
> >

I'm still willing to be convinced, but not by this article.

Ctein writes: "I moved the camera to keep the on-film magnification  
[the same]..."

He cheated. He clearly changed his position, and thus, the  
perspective. Sure, that changes DOF! But it would have changed it no  
matter the focal length.

I will be convinced if he stands *at the same point* and shoots with  
the 25mm and 300mm lenses and a crop of the former to match target  
sizes shows DOF different than the latter. But I've actually done that  
to satisfy my own curiosity, and the DOF was identical.

SUMMARY: if you move back and forth, it isn't the focal length that's  
changing DOF, it's the perspective.

I'm still willing to be convinced, but you'll have to come up with  
something better than Ctein's article. :-)

:::: There is no hope for any of us outside of a community. — Mike  
Ruppert ::::
:::: Jan Steinman, EcoReality http://www.EcoReality.org ::::



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